Heterojunction silicon solar cells obtained by hot-wire CVD at low temperature

In this work, first results on bifacial heterojunction solar cells incorporating thin silicon films by Hot-Wire CVD are presented. The heterojunction with intrinsic thin layer concept applied to the back contact avoids the high temperature anneal usually required for back surface field formation. Both p- and n-type crystalline silicon substrates have been considered. Contactless quasi-steady-state photoconductance measurements evidenced implicit open circuit voltages over 600 mV for heterojunction solar cells by HWCVD. Preliminary devices were fabricated with n-doped amorphous silicon emitter and p-doped microcrystalline silicon back contact. Intrinsic amorphous silicon buffer layers 5 nm thick were used in both sides. The maximum temperature in the whole fabrication process was 200 °C. The best solar cell yielded an active area conversion efficiency of 9.8% with an open circuit voltage of 577 mV, short circuit current of 26.1 mA·cm ^-2 and fill factor of 65%.